Improving waveform for FDA-MIMO-based DFRC systems by collaborating modulation and optimization

The dual-function radar-communication (DFRC) system based on frequency diverse array multiple-input multiple-output (FDA-MIMO) has garnered significant attention. However, designing a promising integrated waveform for an FDA-MIMO-based DFRC system remains a challenge due to the limitations inherent in existing modulation and optimization methods. This paper proposes a new hybrid index modulation (HIM) method that dynamically selects communication subpulses and frequency offsets to transmit information in a flexible and efficient manner, thereby achieving high data rates and low bit error rates. Building upon the proposed HIM, we minimize the beampattern integrated sidelobe level to enhance detection capability, while accounting for multiple practical constraints to ensure that the optimized integrated waveform is hardware-compatible and meets communication requirements. Furthermore, we decompose the formulated problem by using the strong coupling-based alternating direction method of multipliers, and introduce progressive approximation-guided optimization and alternating optimization with successive convex approximation to obtain the optimal frequency offset unit and waveform. Simulation results demonstrate that the proposed integrated waveform design method outperforms existing approaches in terms of both radar and communication performance.